Early Detection of Chemotherapy‐Induced Glucose Metabolic Alterations in Bladder Carcinoma Using Deuterium ( ² H) Metabolic Imaging: in Vitro and in Vivo Assessments

Deuterium metabolic imaging (DMI) is a promising noninvasive technique for assessing tumor metabolism, yet its application in bladder cancer (BCa) remains unexplored. This study presents the first demonstration of DMI for evaluating therapeutic response in BCa through in vitro and in vivo experiments. Two types of deuterium-labeled glucose tracers, [6,6'-²H₂]-D-glucose and [2,3,4,6,6'-²H₅]-D-glucose, are systematically compared for their efficacy in capturing glycolytic activity and treatment-induced metabolic changes in BCa models. In subcutaneous tumors, deuterium magnetic resonance spectroscopy and spectroscopic imaging reveal pronounced suppression of glycolytic flux following chemotherapy, underscoring the potential of DMI for early therapeutic response assessment in BCa treatment. Both tracers consistently detect these chemotherapy-related metabolism shifts in both vitro and in vivo experiments, indicating the translational advantage of [2,3,4,6,6'-²H₅]-D-glucose as a cost-effective alternative to [6,6'-²H₂]-D-glucose. Notably, subcutaneous administration yields metabolic profiles comparable to intravenous delivery. Finally, the optimized lower-dose, subcutaneous [2,3,4,6,6'-²H₅]-D-glucose protocol is successfully validated in orthotopic BCa models. These results demonstrate DMI as a reliable tool for non-invasive monitoring of therapeutic response in BCa, with practical potential for future clinical translation.